South-east Asian idylls – from Philippine islands to the Thai bay made famous in The Beach – plan to turn tourists away so that devastated coral reefs have some time to recover. Will it be enough?

Our Thai tour guide, Spicey, takes a drag on her cigarette and gestures sadly towards the beach. “The problem with people is that they are too greedy. They see a beautiful place and they want it. They take, take, take from nature. And then they destroy it.”

The golden sands of Maya Bay where Spicey stands are some of the most famous in the world. This once-idyllic cove, on the tiny Thai island of Koh Phi Phi Leh, was the paradise location of The Beach, Danny Boyle’s 2000 film starring Leonardo DiCaprio. It was then pushed by tourism officials in advertising campaigns to entice more wealthy visitors to Thailand.

An innovative exchange of sovereign debt for marine conservation, backed by the likes of Leonardo DiCaprio, could pave the way to saving large swaths of the world’s oceans

The tropical island nation of Seychelles is to create two huge new marine parks in return for a large amount of its national debt being written off, in the first scheme of its kind in the world.

The novel financial engineering, effectively swapping debt for dolphins and other marine life, aims to throw a lifeline to corals, tuna and turtles being caught in a storm of overfishing and climate change. If it works, it will also secure the economic future of the nation, which depends entirely on tourism and fishing. With other ocean states lining up to follow, the approach could transform large swaths of the planet’s troubled seas.